Locking device for turbine rotor blades



Aug. 24, 1965 JAMES E. WEBB 3,292,393

ADMINIsTRAToR OF THE NATIONAL AERoNAuTIcs AND SPACE ADMINISTRATION LOCKING DEVICE FOR TURBINE ROTOR BLADES Filed Nov. 5, 1962 2 Sheets-Sheet l I i' ID I] Q6 24 II i I 44 42 i' C25 23 -12 Jsz H A. Gioooz/cl-l KENNETH Z INGHAM INVENTORS BY W -'W ATTOEHEVS g- 1965 JAMES E. WEBB ADMINISTRATOR OF THE NATIONAL AERONAUTICS AND SPACE ADMINISTRATION LOCKING DEVICE FOR TURBINE ROTOR BLADES 2 Sheets-Sheet 2 Filed Nov. 5, 1962 JOSEPH A ($00021 CH KENNETH T, I NGHAM INVENTORS ATTORNEYS turned tab or projection 44 respectively, the tabs being disposed on the terminal ends of leg 26. The circumferential length of notches 38 and 40 is substantially equivalent to one-half the width of the corresponding tab,

and the axial depth of notches'SSand 4%) is substantially equivalent to the thickness of each corresponding tab.

As a result the tabs 42 and 44 are disposed within the corresponding notches so that aerodynamic interference or turbulence is not created during rotation of the turbine wheel.

Originally, leg 26 is made long enough so that the 'length of the tabs 42 and 4-4, when formed, is more than adequate for completely engaging the blade platforms.

I After the tabs are formed, they are trimmed so that the terminal edge of each tab is in substantially the same plane as the upper surface of the blade platform. Thus, it may key 5% will not adversely affect the operation of the turbe seen that the tabs, in combination with the arms 28,

prevent axial movement of blades 14.

In the event either one of the tabs 42 or 4% fails on 'one of the keys 24, the tab remaining will contribute to retaining the respective blades on the turbine wheel,

until such time as repairs can be performed, and'in the eventboth tabs of a single key are lost, the keys on each side of the damaged key will contribute to retaining 'the corresponding blades on the turbine wheel until such time as repairs become convenient.

Because of the width of eachrarm 28, there is little likelihood that either one or both of the arms 28 can be sheared from leg 26 under normal usage. However,

,if one arm 28 is sheared from leg 26, the opposite arm will retain the key 24 in the recess 39 until such time as itis convenient to replace the damaged key. FIGS. 5-8- inclusive, illustrate another form of key 5 which, initially, comprises a pair of substantially identical L-shaped members 52 which preferably are welded, brazed, or otherwise fastened together with the upturned short leg or tab 54 of each member being in abuttingrelationship with the adjoining short leg or tab of the oppowardly. However, it. is to be understood that members 52- need not be fastened together, but instead can be employed as separate members which in combination provide single key 50. The key shown in FIG. 6 is symmetrical in a manner like that of the key shown in FIG. 2. That is, a plane that is perpendicular to the keys longitudinal axis and that passes through the center of gravity of thekey, will divide it into two similar halves; and a second plane containing the longitudinal axis of the key and that also passes through its center of gravity will also divide it into two similarhalves about that plane (note the twofZ shaped cross'sections of each half in FIG. '7). i

The crown 32 of each turbine wheel projection 34 has an elongated axial channel or recess 56 in a circumferential plane which is complementary to and receives key 50 which when installed is in underlying relationship to a true with respect to tabs 54.

While the present invention has been described herein in What is considered to .be preferred embodiments thereof,

.site member. When parts 52--52 are assembled as shown a in FIG. 6, the entire assembly looks like a T lying on its back with the central leg or stem (tabs 54) facing up bine Wheel since the opposite tab of the key will assist in retaining the respective blades on-the wheelltl until repairs .can be performed, andrthe loss of both tabs 54 of a single key 53 will not require taking the turbine out of operation, for the keys 5t) on each side of the damaged key will retain the blades on the turbine Wheel until repairs are convenient to' make. With respect to performing repairs and the like, the same thing holds true withres'pect to the loss of tabs or projections 68 as holds it should be recognized that departures may be made therefrom within the scope of the invention, and it should therefore not be limited to the details of the disclosure, but should be claims.

What is claimed is':

1. A turbine rotor having axial spaced opposite faces, spaced, axially extending peripherally dovetailed grooves therein defining projections'between the adjacent grooves, each of said projections having an axial channel in the peripheralsurface thereof. extending to the opposite axial faces of the rotor, saidchannels having identically opposed circumferentially extending recesses communicating with each of said channels, blades having dovetailed groove projections interengaging said'dovetailed grooves in said rotor and having circumferen-tially extending platforms overlying said projections and the channels and recesses therein, each of said platforms having axially spaced ends terminating in the corresponding plane ofthe axial opposed ends offlthe rotor, a recess 'in each end of the said platform overlying said projections andthe channels therein and complementary to said channels, a key in each of said channels having "projections thereon fitting the identically opposed recesses and underlying said platforms, .andaprojection in each end of said key fitting the recesses in each end of the platform to prevent the blades from being axially displaced from the rotor.

, 2. A .turbinev rotor having axially spaced opposite faces,

faxiallyextending peripheral grooves therein defining propair of adjoining, substantially abutting blade platforms Y 20, the platforms preventing the keys from being thrown radially from turbine wheel 15} during rotation thereof.

Each end 58 of each blade platform has a notch therein which is disposed substantially midway between the for- .ward and the rear edges of and 62 respectively.

the notches of adjoining blade platforms in register, a relatively large notch 64 is provided which receives abutting legs 54 of members 52. The upper edge of each leg 54 when properly trimmed is in substantially the same plane as the upper surface of blade platform 20. The

blades and key locks are all assembled at one time onto the turbine wheel. That is, any type of a jig can be providedthat will support the blades with keys in place in a circle. The blades and keys can then all be slid off the jig and onto the turbine Wheel at the same time, in the way that a piston ring would be slipped onto a piston With ventially extending platforms overlying said projections .1mm passes through the center of gravity of saidkey and jectionsibetween the'adjacent grooves, each of said projections having an axial channel; in the periphcralsurface thereof extending to-the opposite axial faces of the rotor,

fsaid channel having a smooth'bottom surface lying in .a

circumferential plane, blades having portions interengaging withsaid grooves in said rotor toprevent radial displacement of said blades,,said'blades having circumferand the channels, each of said platforms having axially spaced ends, recesses in each of said platforms overlying said projections and the channels therein, a key havinga longitudinal axis and being symmetrical about a plane perpendicular to the longitudinal axis, said'key having a .smooth undersurface' portion-thereof complementary to V and receivablein said channel, and prevented by the walls of .said channel from'being displaced circumferentially, said portionof the key and complementary'channel being .syrr'nnetricahso asto avoid introducing an unbalanced condition in said turbine rotor when the blades are installed in position, a projection on said key engaging said rotorproje'ction toprevent displacement of said key, and

accorded the full scope of-the appended M a tab on said key engaging adjoining blade recesses to prevent axial displacement of said adjoining blades.

3. A turbine rotor having axially spaced opposite faces, spaced, axially extending peripheral grooves therein defining projections between the adjacent grooves, each of said projections having an axially cruciform channel in the peripheral surface thereof extending between the opposite axial faces of the rotor, blades having portions interengaging with said grooves in said rotor to prevent radial displacement of said blades, said blades having circumferentially extending platforms overlying said projections and the channels, each of said platforms having axially spaced ends, a recess in each of said platforms overlying a projection and the channel therein, a substantially fiat cruciform key having a configuration complementary to and receivable in said channel, and underlying a pair of adjoining blades, the arms and legs of said cruciform key laying in the same circumferential plane, the arms of said cruciform key preventing displacement of said key, and said cruciform key having a tab on each terminal end of the leg of said lrey which engages said adjoining blades to prevent displacement of said adjoining blades axially and circumferentially.

4. A device as set forth in claim 3 wherein each of said blades have a platform that is quadrilateral and said (Lil 5. A construction according to claim 2 wherein each of said blades have recesses therein disposed intermediate the axially spaced ends of each of said blade platforms, and that are in registration to receive said tab when said blades are in adjoining relationship.

6. The device as set forth in claim 2 wherein said key comprises two Z-shaped members in end-to-end relation to provide a pair of tabs that are in abutting relationship, and wherein said blades each include a blade platform having recesses therein disposed intermediate the axially spaced ends of each of said blade platforms, and when said blades are in adjoining relationship said recesses are in registration to receive said pair of tabs.

References Cited by the Examiner UNETED STATES PATENTS 2,942,842 6/69 Hayes 25377 3,157,385 11/64 Jensen 253-77 FOREIGN PATENTS 671,960 5/52 Great Britain. 715,837 9/54 Great Britain.

OTHER REFERENCES German printed application No. 1,032,753, June 26,

DONLEY J. STOCKING, Primary Examiner.

JOSEPH H. BRANSON, 1a., KARL J. ALBRECHT,

HENRY F. RADUAZO, Examiners. 

1. A TURBINE ROTOR HAVING AXIAL SPACED OPPOSITE FACES, SPACED, AXIALLY EXTENDING PERIPHERALLY DOVETAILED GROOVES THEREIN DEFINING PROJECTIONS BETWEEN THE ADJACENT GROOVES, EACH OF SAID PROJECTIONS HAVING AN AXIAL CHANNEL IN THE PERPHERAL SURFACE THEREOF EXTENDING TO THE OPPOSITE AXIAL FACES OF THE ROTOR, SAID CHANNELS HAVING IDENTICALLY OPPOSED CIRCUMFERENTIALLY EXTENDING RECESSES COMMUNICATING WITH EACH OF SAID CHANNELS, BLADES HAVING DOVETAILED GROOVE PROJECTIONS INTERENGAGING SAID DOVETAILED GROOVES IN SAID ROTOR AND HAVING CIRCUMFERENTIALLY EXTENDING PLATFORMS OVERLYING SAID PROJECTIONS AND THE CHANNELS AND RECESSES THEREIN, EACH OF SAID PLATFORMS HAVING AXIALLY SPACED ENDS TERMINATING IN THE CORRESPONDING PLANE OF THE AXIAL OPPOSED ENDS OF THE ROTOR, A RECESS IN EACH END OF THE SAID PLATFORM OVERLYING SAID PROJECTIONS AND THE CHANNELS THEREIN AND COMPLEMENTARY TO SAID CHANNELS, A KEY IN LEACH OF SAID CHANNELS HAVING PROJECTIONS THEREON FITTING THE IDENTICALLY OPPOSED RECESSES AND UNDERLYING SAID PLATFORMS, AND A PROJECTION IN EACH END OF SAID KEY FITTING THE RECESSES IN EACH END OF THE PLATFORM TO PREVENT THE BLADES FROM BEING AXIALLY DISPLACED FROM THE ROTOR. 